1. Field of the Invention
This invention relates to a novel bis(hydroxyphthalimide) and a process for preparing the same, and also relates to a process for preparing a polyesterimide using the aforementioned bis(hydroxyphthalimide).
2. Related Art Statement
It has been known in the art that a compound having therein an imide ring has excellent heat resisting property, and that a polyimide is particularly superior in heat resisting property amongst the known heat resisting polymers. The polyimide resins having such advantageous properties have been widely used in the arts of aerospace and aeroplane engineerings, and also in general industrial fields for the production of printed circuit boards, package materials, varnishes for coating electric wires, etc. By the incorporation of an imide ring in a certain polymer, the heat resistant property of the polymer is improved by the advantageous influence afforded by the introduced imide ring. For example, there is a report describing that the heat resistant property of an epoxy resin has been improved by the introduction of an imide ring so that the maximum durable temperature of the modified resin is raised by about 100.degree. C. The polymers having intramolecular imide rings, including polyimides, are expected for further development in view of their excellent heat resistant properties. However, the known polyimides have a disadvantage that they are inferior in percent transmission to visible light rays. Another barrier arresting the development of polyimide resins is that the monomer which may be used as a starting material for a variety of imide ring-containing polymers, as comparable to bisphenol A used for preparing various polymers, is not yet known, although various polyimides or imide ring-containing polymers have been synthesized and used.
After eager pursuit to find an imide ring-containing monomer which may be used as a starting material for the preparation of various imide ring-containing polymers, we have found that a novel bis(hydroxyphthalimide) which is adapted for use as a starting material for various imide ring-containing resins. The bis(hydroxyphthalimide) provided by the invention affords a further merit that a polyesterimide excellent both in transparency and heat resistant property is produced therefrom.
The novel bis(hydroxyphthalimide) provided by the present invention is represented by the following general formula of: ##STR1## wherein R is a difunctional organic group selected from the group (a), (b) and (c) of:
(a) aromatic hydrocarbon groups having 6 to 20 carbon atoms or a halogenated derivatives thereof;
(b) alkylene groups: and
(c) those represented by the following general formula of: ##STR2## wherein X is a group selected from the group consisting of --O--, ##STR3## --S--, --C.sub.n H.sub.2n --; m is an integer of 1 or zero; and n is an integer of 1 to 5.
The novel bis(hydroxyphthalimide) set forth above may be prepared by reacting 4-hydroxyphthalic anhydride with an organic diamine represented by the following general formula in the presence of an organic solvent: EQU H.sub.2 N--R--NH.sub.2
wherein R is the same as defined above.
Examples of organic diamine which may be conveniently used in the preparation of the bis(hydroxyphthalimide) in the present invention include m-phenylendiamine, p-phenylenediamine, 4,4'-diaminodiphenylpropane, 4,4'-diaminodiphenylmethane, benzidine, 4,4'-diaminodiphenylsulfide, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3'-diaminobenzidine, 3,3'-dimethoxybenzidine, 2,4-bis( -amino-t-butyl)toluene, bis(p- -amino-t-butylphenyl)ether, bis(p- -methyl-o-aminobenzyl)benzene, 1,3-diamino-4-isopropyl benzene, 1,2-bis(3-aminopropoxy)ethane, m-xylylene diamine, p-xylylene diamine, 2,4-diaminotoluene, 2,6-diaminotoluene, bis(4-aminocyclohexyl)methane, 3-methylheptamethylenediamine, 4,4-dimethylhepatamethylenediamine, dodecamethylenediamine, 2,2-dimethylpropylenediamine, octamethylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylhepamethylenediamine, 5-methylnonamethylenediamine, 1,4-cyclohexanediamine, octadecamethylenediamine, bis(3-aminopropyl)sulfide, N-methyl-bis(3-aminopropyl)amine, hexamethylenediamine, heptamethylenediamine, 4,4'-diaminobenzophenone, nonamethylenediamine, decamethylenediamine, bis(3-aminopropyl)tetramethyldisiloxane, and bis(4-aminobutyl)tetramethyldisiloxane.
In the practice of the aforementioned reaction, substantially 2 mols of 4-hydroxyphthalic anhydride is used per 1 mol of an organic diamine. However, the amount of the organic diamine mixed with 2 mols of 4-hydroxyphthalic anhydride may be varied within the range of from 0.8 to 1.2 mols to give good results.
As the examples of usable solvent, phenolic solvent and glacial acetic acid may be mentioned. Examples of the phenolic solvents are o-cresol, p-cresol, m-cresol and mixtures thereof. When a phenolic solvent is used, it is used in a ratio such that 1 to 2 parts by weight or more thereof is added per 1 part by weight of the total weight of the reactive ingredients. Preferable reaction temperature ranges between about 100.degree. to 140.degree. C. In order to remove the water produced by the reaction for forming the bis(hydroxyphthalimide) from the reaction system, a non-polar solvent having a low boiling point and forming an azeotropic mixture with water, such as benzene, chlorobenzene or toluene, may be used.
The time required for the reaction is varied depending on the parameters, such as the specific kind of organic diamine used, the extent of stirring and the reaction temperature, and generally ranges from 20 minutes to 2 hours. After the completion of reaction, the reaction mixture is cooled and then the solvent is removed under a reduced pressure. Alternatively, the reaction mixture may be added to another solvent, such as methanol, to precipitate the reaction product which is then isolated by filtration.
When glacial acetic acid is used as the solvent in the aforementioned reaction, glacial acid is added in a ratio such that about 10 parts by weight thereof is present per 1 part of the total weight of all reactive ingredients. The reaction is continued for 1 to 15 hours under the reflux of glacial acetic acid. After the completion of reaction, the reaction system is cooled and the precipitate is filtered and rinsed with methanol to isolate the product bis(hydroxyphthalimide).
The bis(hydroxyphthalimide) of the invention may be polycondensed with a dicarboxylic acid dihalide to produce a polyesterimide. The thus prepared polyesterimide, included within the broad scope of this invention, is of high industrial value in that it has excellent heat resistant property and superior transparency.
Specific examples of the bis(hydroxyphthalimide) which may be used as a starting material for the production of the polyesterimides according to the invention are 1,3-bis(4-hydroxy-phthalimide)benzene and 1,4-(bis-hydroxyphthalimide)benzene.
Specific examples of the dicarboxylic acid dihalide are halogenated products of dicarboxylic acids such as terephthalic acid, isophthalic acid, phthalic acid, phenylmalonic acid, phenylsuccinic acid, benzylsuccinic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, methylsuccinic acid and adipic acid. The dicarboxylic acid dihalides, which may be used conveniently in the reaction, are represented by the following general formula of: ##STR4## wherein R.sub.2 is a difunctional organic group selected from the groups (a), (b) and (c) of:
(a) aromatic hydrocarbon groups each having 6 to 20 carbon atoms or halogenated derivatives thereof;
(b) alkylene groups; and
(c) those represented by the following general formula of: ##STR5## wherein X is selected from the group consisting of --O--, ##STR6## --S-- and --C.sub.n H.sub.2n --; m is an integer of 1 or zero; and n is an integer of 1 to 5;
and wherein Y is any one of fluorine, chlorine, bromine or iodine; and Z is any one of fluorine, chlorine, bromine or iodine.
The bis(hydroxyphthalimide) may be represented by the following general formula of: ##STR7## wherein R.sub.1 is a difunctional organic group selected from the groups (a), (b) and (c) of:
(a) aromatic hydrocarbon groups having 6 to 20 carbon atoms or a halogenated derivative thereof;
(b) alkylene groups; and
(c) those represented by the following general formula of: ##STR8## wherein X is a group selected from the group consisting of --O--, ##STR9## --S--, --C.sub.n H.sub.2n --; m is an integer of 1 or zero; and n is an integer of 1 to 5.
On the other hand, the polyesterimides obtained by the polycondensation reaction may be represented by the following formula of: ##STR10## wherein R.sub.1 and R.sub.2 are the same as described in the general formulae representing the bis(hydroxyphthalimide) and the dicarboxylic acid dihalide.
The polycondensation reaction for preparing the polyesterimide of the invention may be effected in a polar organic solvent substantially in the absence of water. An amide system organic solvent, such as N-methyl-2-pyrrolidone, N,N-dimethylformamide or N,N-dimethylacetoamide, is used after drying the same sufficiently. A tertiary amine, such as pyridine or triethylamine, may be added to the reaction system, in order to remove hydrogen halides produced as the reaction proceeds.
The polycondensation reaction is carried out by adding substantially 1 mol of a dicarboxylic acid dihalide per 1 mol of the bis(hydroxyphthalimide). The reaction temperature ranges from 20.degree. to 50.degree. C., and the time required for the completion of reaction is varied depending on the specific kinds of the reactant, the reaction temperature and the extent of stirring and generally ranges from 30 minutes to 30 hours. After the completion of reaction, the reaction mixture may be added into a solvent, such as methanol, and the sedimented precipitate may be filtered to isolate the formed polyesterimide.
Other than the process wherein an organic solvent is used, an interfacial polymerization as disclosed in the "Journal of Polymer Science", vol. XL, 399 (1959) may be used. In the interfacial polymerization process, an aqueous alkali solution of bis(hydroxyphthalimide) is subjected to the interfacial polymerization with an solution of a dicarboxylic acid dihalide in an organic solvent.